An API key with report access + your vendor number unlock the install → purchase funnel and per-country App Store analytics.
App Store Connect powers the funnel view — impressions → product-page views → downloads — and per-country App Store analytics, which sharpen plans and diagnostics. It's optional and read-only. (A Growth-plan feature.)
What you need
Issuer ID and Key ID — shown on the API keys page.
The .p8 private key — downloadable exactly once.
Your Vendor Number — lives on a different page (step 3).
Paste everything in AdsBuddyOnboarding step 2 or Settings → Integrations → App Store Connect: Issuer ID, Key ID, Vendor Number and the .p8 contents (file picker available).
Analytics data from Apple arrives with a delay (typically 2–4 days) — that's Apple's pipeline, not a sync problem. The funnel fills in as data lands.